Seam lock foe stove pipes



July 2, 1935. J. J. HOLUB 2,006,863

SEAM LOCK FOR STOYE PIPES Filed Sept. 14, 1954 I72 venr: Jan/v J H01. U8

Patented July 2, 1935 f UNITED STATES PATENT OFFICE 'My present invention pertains to sheet-metal pipes such as are employed in connection with stoves, furnaces, and other structures, for conducting ,air, smoke and similar gaseous elements from the heating structure to different locations, and also for leading air back to the furnace when the latter is of the warm-air or recirculating type. V i

In fabricating conductor pipes it has been the practice to utilize a rectangular blank or" sheetmetal that is rolled into cylindrical form or terete and to provide an intercalated or interlocked seam to join the overlapped or meeting edge portions of the blank. This seam has usually been made by forming shoulders and oliset portions along the longitudinal proximate edges or the blank, and then forming reverse bends intermediate the widths of theoiT-set portions. Thus the free edge portions orfiaps that extend from the bends to the adjacent edges of the blank may be interlocked by hooking each with the other, and when assembled the interhooked elements prevent relative circumferential movement in a single direction; that is, in a direction that would enlarge the diameter of the finishedpipe. Attempts have also been made to prevent relative circumferential movement in the direction reverse to that just mentioned, which movement would tend tounlock and release the interlocked or interhooked flaps of the seam. Most of such attempts. have had inherent defects in the structures with the result that they have met with uncertain success.

With the structure disclosed herein I have provided a very positive lock that successfully prevents attempts to move the joined or seamed edges in both circumferential directions, except after a distinct distortion of the pipe as when it is desired to unlock the same. Such distortion is necessary for the purpose of both unlocking and in assembling the structure.

Mr present lock-seam for stove-pipes is novel in construction, it is dependable in performing its functions; it is easy to manipulate either for looking or unlocking; and it is economical to manufacture, so that it may be sold to the consumer for a reasonable retail price. The foregoing are some of the objects and advantages which I' have had in'mind in devising my improved lock-seam, and others will be apparent to persons skilled in the art after my structure is understood.

I prefer to accomplish the numerous objects, and to practice my invention, in substantially the manner hereinafter described and as more particularly pointed out in the claims. erence is made: to the accompanying drawing that forms a part of this specification, in which drawing,

Ref-

Fig. 1 is a fragmentary view in elevation showing my improved lock-seam applied to a metal p p Fig. 2 is a transverse horizontal section thereof taken on line 2-2 of Fig. 1, looking in the direction of the arrows and drawn to an eX- aggerated scale for clearness.

Fig. 3 is another transverse horizontal section taken on line 3-3 of Fig. 1, looking in the direction of the arrows, and drawn to the same scale as Fig. 2.

Fig. 4 is a plan of an edge portion of the metal blank showing the arrangement of the parts forming one side of the lock seam.

Fig. 5 is another view of the structure shown in Fig. 4, disclosing the first fold or reverse bend to provide the lock-seam.

Fig. 6 shows the two proximate edges of a pipe body or blank after the second or final reverse bend has been made, therespective left-hand and right-hand edge portions of the body being disposed in the relative position for the initial step of the assembly or'interhooking of the lock seam.

The pipe consists of an initially flat rectangular body or blank H) of sheet-metal of the de- 1 sired gage, that is rolled or otherwiseformed so that the completed pipe is of cylindric shape or terete in cross-section. To complete the pipe the proximate edges of the blank are brought together and interlocked by means of an intercalated seam.

Both longitudinal edges of the body Ill have several elongated notches H cut therein, and

said notches are spaced from each other to provide a plurality of laterallyv projecting tongues l2, I3, along the respective edges. The upper edges of the respective tongues are tapered or oblique as indicated at Ir Ili so that said tongues are shortened along their outer longitudinal edges, the purpose. of which will be hereinafter more fully explained.

For convenience, one longitudinal edge only, the left-hand edge, of the blank isshown in Figs; 4 and 5, but it will be understood that the other edge, the right-hand edge, is provided with similar notches and tongues.

Each of these edges of the blank is given a re" verse bend along the plane of dot-and-dash line a: that passes lengthwise through the tongues. This reverse bend disposes the free ends of the left-hand edge tongues on the outside of the body, whilethe bend at the opposite '(righthand) edge positions the free edges of its tongues on the other or inside the body.

A second reverse bend is made in thebody of the blank back of the notches along the plane of dot-and-dash line 1/ at each longitudinal edge tive seam flaps. An S or Z bend is also made in the body of the blank back of the already folded portions and near each of the proximate edges. These S-bends provide shoulders or abutments i s extending longitudinally of the body alongside and slightly spaced from the folded edges formed by the reverse bends at. Said S-bends also provide off-set portions that extend longitudinally along each edge portion of the body and are wide enough so that the two reversely bent sections are disposed or included in said oil-set portions.

It will be seen that the double, reverse bends :c and y provides seam flaps A and B that extend along the respective longitudinal edges of the body on the opposite faces thereof, so that they may be interengaged or hooked with each other when the longitudinal edges are assembled with each other as seen in Fig. 3. The tongues i2 and I3 at each edge are folded inside their respective flaps A and B, and said tongues are disposed normally opposite each other so that they may be interengaged or hooked with each other when the structure has been assembled.

In assembling the structure to interfit or interlock the scam, the blank or body is held in cylindrical form with the seam edges toward each other and the body is then warped slightly as schematically shown in Fig. 6. This disposes the respective corners of the body the one above the other, and also disposes tongues 52 and 13 of the flap B opposite the recesses or notches ll of the flap A. The proximate edges are then overlapped with each other and the flap B, with its tongues, is inserted or hooked under flap A by a circumferential relative movement so that the edge at the piece at the right in Fig. 6 will be between the shoulder M and the folded portions of the tongues of the left piece shown in said figure and it will abut the shoulder of said left piece. The same relation is true in connection with the edge of the left piece (Fig. 6) which will have its extreme edge abut the shoulder of the right piece.

After this initial engagement is made the respective portions are moved or slid longitudinally in opposite directions as indicated by arrows in Fig.6, which movement will cause the tongues l2 and I3 of one seam edge to insert themselves in, interlocked or interhooked relation with the corresponding tongues of the other seam edge as shown in enlarged detail in Fig. 2.

An effective and dependable lock is thus provided that positively prevents relative movement of the respective edges in either direction circumferentially of the completed pipe. Any tendency to contract the pipe is prevented by the outer bends y of the flaps abutting the adjacent shoulders 2 and also by the tongues I2-i 3 engaging inside the bends .212, while tendency to expand the pipe is prevented by the interhooked disposition of the respective parts which causes bends x to engage inside the bends y. However, the seam may be readily unlocked and separated by simply reversing the before-mentioned steps. The oblique portions l3 provide the notches with outer portions or mouths that are wider than their inner portions to facilitate the entry of the projecting portions of the opposite tongues, and such oblique portions also tend to guide the adjacent end edges of'the flaps when entering the notches. It is to be noted that the reverse bends :1: lie in intermediate portions of the tongues so that the portions of the tongues that are back of the bends form projections along the free edges of the respective flaps with the notches or recesses H between them, and it is these projections on one part of the scam that are inserted into the notches H of the opposite part of the seam when the assembly is being made.

It will be appreciated that instrumentalities other than those specifically disclosed herein may be employed in carrying out my invention, and I therefore desire itunderstood that modifications and changes may be made in the structure herein described and shown without departing from the principles involved, and such modifications and changes are contemplated within the scope of the appended claims.

What I claim is:

1. A sheet metal structure comprising two metal edges joined together, both edges being bent back on themselves to provide flaps forming an interlocking joint permitting longitudinal movement along the joint, each flap edge carrying an extension turned inwardly to lie substantially parallel with the sheet body in the space between the body of the sheet and its flap said extensions being also adapted to interlock when the sheets are longitudinally moved with respect to each other so that said extensions are overlapping and slide into interlocking position.

2. A sheet metal structure comprising two metal edges joined together, both edges being bent back on themselves to provide flaps forming an interlocking joint permitting longitudinal movement along the joint, each flap edge carrying spaced extensions turned inwardly to lie substantially parallel with the sheet body in the space between the body of the sheet and its flap, the respective extensions being also adapted to interlock when the sheets are longitudinally moved with respect to each other so that said extensions are overlaping and slide into inter locking position.

3. A stove-pipe comprising a sheet of metal bent into tubular form to present two meeting edges forming a seam, both meeting edges of the sheet being bent back on themselves to provide flaps forming an interlocking joint permitting longitudinal movement along the joint, each edge flap carrying an extension turned inwardly to lie substantially parallel with the sheet body in the space between the body of the sheet and its flap, said extensions being also adapted to interlock when the edges of the sheet are longitudinally moved with respect to each other so that said extensions are overlapping and slide into interlocking position.

4. A stove-pipe comprising a sheet of metal bent into tubular form to present two meeting edges forming a seam, both meeting edges of the sheet being bent back on themselves to provide flaps forming an interlocking joint permitting longitudinal movement along the joint, each edge flap carrying spaced extensions turned inwardly to lie substantially parallel with the sheet body in the space between the body of the sheet and its flap, the respective extensions being also adapted to interlock when the edges of the sheet are longitudinally moved with respect to each other so that said extensions are overlapping and slide into interlocking position.

JOHN J. HOLUB. 

